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Screening for triazole resistance in clinically significant Aspergillus species; report from Pakistan
Safia Moin1, Joveria Farooqi2, Kauser Jabeen1
1Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan.
Background:
Burden of aspergillosis is reported to be significant from developing countries including those in South Asia. The estimated burden in Pakistan is also high on the background of tuberculosis and chronic lung diseases. There is concern for management of aspergillosis with the emergence of azole resistant Aspergillus species in neighbouring countries in Central and South Asia. Hence the aim of this study was to screen significant Aspergillus species isolates at the Microbiology Section of Aga Khan Clinical Laboratories, Pakistan, for triazole resistance.
Methods:
A descriptive cross-sectional study, conducted at the Aga Khan University Laboratories, Karachi, from September 2016-May 2019. One hundred and fourteen, clinically significant Aspergillus isolates [A. fumigatus (38; 33.3%), A. flavus (64; 56.1%), A. niger (9; 7.9%) A. terreus (3; 2.6%)] were included. The clinical spectrum ranged from invasive aspergillosis (IA) (n = 25; 21.9%), chronic pulmonary aspergillosis (CPA) (n = 58; 50.9%), allergic bronchopulmonary aspergillosis (ABPA) (n = 4; 3.5%), severe asthma with fungal sensitization (SAFS) (n = 4; 3.5%), saprophytic tracheobronchial aspergillosis (n = 23; 20.2%). Screening for triazole resistance was performed by antifungal agar screening method. The minimum inhibitory concentration (MIC) of 41 representative isolates were tested and interpreted according to the Clinical and Laboratory Standards Institute broth microdilution method.
Results:
All the isolates were triazole-susceptible on agar screening. MICs of three azole antifungals for 41 tested isolates were found to be ≤1 ml/L; all isolates tested were categorized as triazole-susceptible, including 4 isolates from patients previously on triazole therapy for more than 2 weeks. The minimum inhibitory concentration required to inhibit the growth of 90% organisms (MIC90) of itraconazole, voriconazole and posaconazole of the representative Aspergillus isolates was 1 mg/L, 1 mg/L and 0.5 mg/L, respectively.
Conclusion:
Triazole resistance could not be detected amongst clinical Aspergillus isolates from the South of Pakistan. However, environmental strains remain to be tested for a holistic assessment of the situation. This study will set precedence for future periodic antifungal resistance surveillance in our region on Aspergillus isolates.
Insights
This study found no triazole resistance in clinical Aspergillus isolates from Pakistan, despite concerns about antifungal resistance in South Asia. Further environmental testing is recommended for a complete assessment.
Area of Science:
- Medical Mycology
- Antimicrobial Resistance
- Clinical Microbiology
Background:
- Aspergillosis poses a significant health burden in developing countries, particularly in South Asia.
- Pakistan faces a high burden of aspergillosis, often co-occurring with tuberculosis and chronic lung diseases.
- Emerging azole-resistant Aspergillus species in neighboring regions raise concerns for effective aspergillosis management.
Purpose of the Study:
- To screen clinically significant Aspergillus species isolates from Pakistan for resistance to triazole antifungal agents.
- To assess the current status of triazole susceptibility in Aspergillus isolates within the South Asian region.
Main Methods:
- A descriptive cross-sectional study was conducted on 114 clinical Aspergillus isolates (A. fumigatus, A. flavus, A. niger, A. terreus) from September 2016 to May 2019.
- Isolates were screened for triazole resistance using the antifungal agar screening method.
- Minimum Inhibitory Concentrations (MICs) of three azole antifungals were determined for 41 representative isolates using broth microdilution.
Main Results:
- All 114 clinical Aspergillus isolates tested were susceptible to triazoles via agar screening.
- MICs for itraconazole, voriconazole, and posaconazole were ≤1 mg/L for all 41 tested isolates, indicating triazole susceptibility.
- Susceptibility was observed even in isolates from patients with prolonged prior triazole therapy.
Conclusions:
- No triazole resistance was detected in the clinical Aspergillus isolates examined from Southern Pakistan.
- Further studies are needed to assess environmental Aspergillus strains for a comprehensive understanding of antifungal resistance.
- This research establishes a baseline for future periodic surveillance of antifungal resistance in Aspergillus isolates in the region.